28 volt buffer?

Discussion in 'General Electronics Chat' started by chris13409, Feb 2, 2010.

  1. chris13409

    Thread Starter New Member

    Jan 7, 2010
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    What device do I need? I need to buffer some logic levels so they can be sent to a PIC. They vary between 7 to 28 vdc. Is there a buffer that can tollerate 28vdc while drawing very little current The output voltage from the buffer can be anything from 1 to 5 vdc.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You can use an op amp voltage follower with the signal fed to its input. If you want to reduce the output voltage use a voltage divider.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    What kind of tolerance do you have on the translator current?

    You might use a resistive divider and a comparator.
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    Look at MM74C914, schmitt trigger with extended input voltage. Might be close.
     
  5. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    For logic inputs, a simple resistive divider will work fine.

    Three resistors connected to a junction point; 2k2 from the input, 4k7 to ground(0V) and 100K to the PIC input pin.
     
  6. chris13409

    Thread Starter New Member

    Jan 7, 2010
    7
    0
    Thanks guys,

    I think the MM74C914 might do it. These are fault signals, and I usually check them with a multimeter. (I should have said that in the first place.)
    I'm not sure I can use a voltage divider because it'll draw too much current from my system.

    Chris
     
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